Determining optimum disassembly sequences in electronic equipment

This paper presents a study on disassembly sequence generation for electronic equipment. This is particularly useful because adequate end-of-life disassembly becomes crucial as take-back obligations are imposed for environmental reasons. Besides this, the hierarchical structure, typical to electronic products, makes product remanufacturing to an important topic. Methods from disassembly of mechanical assemblies are successfully adapted to these specific challenges. First, a modeling method for assemblies is described, which is aimed at automatically determining the optimum disassembly sequence. It is argued that the information, which is condensed in the connection diagram and the set of precedence relations, is sufficient for the automatic generation of such a sequence. Appropriate use of the precedence relations reduces the size of the model, that can be represented as an AND/OR graph with a restricted number of subassemblies and actions. With disassembly costs and revenues included, the optimum disassembly sequence can be found with standard linear programming software, thus without the need of visiting the complete search space. As a matter of fact, the size of the problem is strongly reduced, as it increases only linear with the number of parts in the assembly. It has been demonstrated that the model nearly instantaneously generates the optimum disassembly sequence. Besides this, the model can generate near optimum sequences as well, which is beneficial if multiple criteria are considered.